N15A-T018 TITLE: Maritime Local Environmental Sensing for Electromagnetic Maneuver Warfare

TECHNOLOGY AREAS: Sensors, Battlespace

ACQUISITION PROGRAM: PMW-120 non-ACAT Future Metoc Capabilities

OBJECTIVE: The objective of this research is to develop a capability for operational forces to measure the full set of environmental state variables (pressure, temperature, absolute humidity, wind speed and direction, cloud liquid water content, precipitation type and rate, turbulence and aerosol concentrations) remotely from a single fixed position on the exterior decks or mast, at multiple vertical levels from the ocean surface (below deck level) to well above the top of the atmospheric boundary layer to approximately 3500 meters. In addition to the mean state at multiple levels, the vertical gradients of temperature and humidity in the surface and mixed layers are of high interest. A multi-sensor system should be designed that is affordable and maintainable in a maritime environment, fits within surface Navy power and size constraints, and to the extent possible is self-calibrating. The system should be eye, radiation, and noise safe for personnel working in the vicinity in normal operational mode. Successful execution of this STTR would support a proof-of-concept demonstration of an at-sea capability.

DESCRIPTION: The Surface Navy has interest in high fidelity prediction of EM and EO propagation from surface ships to support prediction of radar, electronic warfare, and communications systems operation. Additionally, lower tropospheric winds, density, visibility, icing, and turbulence are needed for marine aviation and higher fidelity observation, and prediction is desired for new platforms such as ship-launched remotely piloted aircraft. Currently, the fidelity of numerical prediction programs is limited in part by the fidelity of the locally observed environmental conditions used as input. This project desires to investigate technologies that would enable high fidelity measurement of environmental profiles in the vicinity of a surface ship. Measurements out to the radar horizon, 360 degrees in azimuth, from an elevation starting at the surface near the ship and extending to 90 degrees, with 1 nautical mile horizontal range resolution, 1 degree azimuth resolution, and 5 meter altitude resolution up to 3500 meters are required with accuracies sufficient to enable construction of high fidelity diagnostic profiles. All designs should include "cut-out" capability to allow placement as possible on ships and only radiating/sensing in directions not interfered with by ship superstructure or personnel.

Technologies of potential interest could include, but are not limited to, Doppler LIDAR and LIDAR spectroscopy, ceilometers, passive radiometry, acoustic sounders, and direct measurement of state variables in an integrated design to produce best possible absolute accuracy and precision. Bulk similarity approaches for more limited direct retrievals such as evaporative duct estimates from sea surface (skin or inlet) temperature, near surface air temperature, relative humidity or wet bulb temperature, mean sea level pressure, and cup-and-vane or sonic anemometer wind speed and direction could be considered only as part of a more general solution to the total vertical profile. To the maximum extent possible, the system should be automated and require minimal maintenance and be self-calibrating. In addition, rapid changes in ambient conditions due to natural changes or ship movement require a relatively rapid measuring capability of no more than 30 minute intervals, with a capability to retrieve a partial set of variables at higher repeat intervals. Accuracy roughly equivalent to a calibrated commercial rawinsonde, but without the use of expendable in-situ sensing approach is desired. Small unmanned aerial vehicles (UAVs) are not considered a feasible approach for this particular topic.

There are a variety of commercial sensors currently used in the Navy to estimate the immediate atmospheric and ocean surface environment surrounding maritime surface vessels. Nonetheless, available environmental monitoring approaches all suffer from various disadvantages with respect to the parameters most needed for Naval operations, such as evaluation and prediction of the Electromagnetic (EM) propagation environment for radars and communication systems, the Electro-optic (EO) environment for imaging sensors, laser weapons, and optical communications, and the lower tropospheric weather conditions for maritime aviation. Traditional Naval surface observations of bulk atmospheric pressure, winds, temperature, visibility and humidity are at a single level such as the main deck or superstructure and do not provide vertical profiles or gradients needed for many applications. Estimates for evaporative duct height and refractivity gradient strength are indirect and rely on empirically-based bulk similarity assumptions that are frequently violated, especially in non-equilibrium background states. Direct profiling systems such as rawinsondes require significant cost, maintenance and logistic support for expendable components. Indirect profiling systems such as passive microwave radiometers suffer from relatively coarse vertical resolution, poor absolute accuracy, and do not provide the full set of variables needed for many applications. Differential Absorption, Raman, Backscatter, or Doppler light detection and ranging (LIDAR) has not been developed to retrieve all needed variables in a form factor suitable for maritime applications.

PHASE I: Define, develop and validate the component modules in a realistic environment, a concept for the determination of 3-dimensional environmental state variables that can meet the vertical resolution, timeliness and accuracy requirements as stated in the Description section. A table of directly measured or derived environmental variables sensed, estimated accuracy, precision, and spatial/temporal resolution should be included. Additionally, an estimated final size, weight, power, and cost per copy based on the Phase I design should be included.

Required Phase I deliverables include a report which defines the concept and provides relevant details that shall include hardware designs, and relevant lab measurements validating the feasibility in terms of size, weight, power, and accuracy of the components for the final design. Additional required Phase I deliverables will include proposed metrics and measurement methodologies, schedule, and cost estimate for Phase II as well as the Phase I Final Report.

PHASE II: Refine, develop, demonstrate and validate the hardware and software designs produced in the Phase I effort into a prototype system. Deliverables from the Phase II effort shall include the prototype hardware and software, and a report that documents the performance of the prototype. The small business will produce a prototype package that works in a shipboard maritime environment. Based on Phase I efforts and any redirection from the program office, Phase II will develop, demonstrate and validate the solution.

Required Phase II deliverables will include:
- Design architecture, algorithms and data analytics
- Test plan
- Software executables and source code
- Demonstration of solution effectiveness and relevance in a representative environment
- Suitable ship time will be provided by the ONR Code 32 Sponsor on a UNOLS Research Vessel proxy. Integration/ installation costs will need to be included in the Phase II budget proposal.
- A prototype system that may be optionally retained by the sponsor for further characterization
- Phase II Final report

PHASE III: Refine the prototype system into a product that can be used on a surface Navy combatant, with appropriate user interfaces, and documentation. At the end of the Phase III effort the system should be at a Technology Readiness Level of 7.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Marine weather observing and forecasting, commercial shipping and navigation, environmental monitoring of remote and minimally attended locations could benefit from this technology.

REFERENCES:
1. J.D. Whalen, March 1998, "Comparison Of Evaporation Duct Height Measurement Methods and their Impact On Radar Propagation Estimates." Retrieved from: http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA345694

2. Evaporation Duct Height. Retrieved from: http://www.nrlmry.navy.mil/refract/evapductht.htm

3. S. Chen, J. Cummings, J. Doyle, R.H. Hodur, T. Holt, C. Liou, M. Liu, A. Mirin, J. Ridout, J.M. Schmidt, G. Sugiyama, and W.T. Thompson, 2003, COAMPS™ Version 3 Model Description--General Theory and Equations, NRL Publication, May, 2003, 145. Available from the Naval Research Laboratory, Monterey, CA, 93943-5502. Approved for public release; distribution unlimited. [NRL/PU/7500--03-448.]

4. J. D. Doyle, F. Giraldo, S. Gabersek, "A Multiscale Non-hydrostatic Atmospheric Model for Regional and Global Applications," ECMWF 15th Workshop on the Use of High Performance Computing in Meteorology, 2012.

5. T. Rogers, Q. Wang, and C. Yardim, "Discrimination Data Sources for Estimating Electromagnetic Propagation," National Radio Science Meeting, 2014.

KEYWORDS: Maritime environmental sensors; environmental remote sensing; electromagnetic refractivity and ducting; marine weather observations; unattended meteorological sensors; LIDAR

** TOPIC AUTHOR (TPOC) **

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